Mobile radio networks such as the Global System for Mobiles (GSM) and the Universal Mobile Telecommunications System (UMTS) can provide a facility for communicating data in circuit switched mode or using data packets. In circuit switched mode a physical communications channel is allocated for a logical communications channel throughout a call. For the communication of data packets, the General Packet Radio Service (GPRS) has been developed. GPRS provides support for a packet-orientated service, which attempts to optimize network and radio resources for packet data communications such as for example Internet Packets (IP). The GPRS provides a logical architecture, which is related to the circuit switched architecture of a mobile radio system.
The system for communicating data between a mobile communications user equipment (UE) and a packet data network comprises: a gateway GPRS support node (GGSN) that provides an interface between the packet data network and GPRS/UMTS for communication of data packets over the mobile telecommunications network and a serving GPRS support node (SGSN) that controls communication of data packets between the gateway support node and the user equipment using a radio network controller (RNC) that controls radio resources of the telecommunications network. A Packet Data Protocol (PDP) context request is used to set up a virtual communications channel which allows communication between the GGSN and the UE. Each data packet specifies a single set of quality of service (QoS) parameters and a radio access bearer is supplied by the RNC in accordance with this set of quality of service parameters. Radio resources provided by the mobile telecommunications network for communicating data packets between the UE and the RNC are a valuable commodity and can be a limiting factor in whether or not a particular radio access bearer can be supported, depending upon for example current loading of the network. As such, it is desirable to use the radio resources as efficiently as possible.
European patent EP 1 096 742 A discloses a radio network which is adapted to support the communication of multi-media data to and from a mobile user equipment. The multi-media data may include a plurality of different data types from different data sources. A multi-service Packet Data Protocol (PDP) context is disclosed for use in subscribing to one or more PDP addresses for each data source. The multi-service PDP context is therefore generated for a subscription request for more than one Quality of Service class. Therefore a bearer can be established having a Quality of Service which is appropriate for communicating the data from one of the data sources to and from the mobile user equipment.
International patent application number WO 02/098077A discloses a mobile radio communications network which is arranged to communicate different classes of data bits from the pay load of IP packets over a radio interface. Each data frame which contains the different classes is divided, in either an application layer or in a lower IP layer, into smaller payload fragments, each of the smaller payload fragments containing a different one of the classes of data. The application layer or the IP layer then generates IP packets along with corresponding treatment information. Each IP packet contains a different one of the classes of data bits for transport over the packet radio network. A radio access bearer is established for each IP packet, the bearer having a Quality of Service which can be matched to the class of data provided in the payload.